Search found 46 matches

by davidryan3f
Sun Feb 10, 2019 10:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Delta H and Delta U
Replies: 1
Views: 8

Delta H and Delta U

What is the difference between Delta H and Delta U?
by davidryan3f
Mon Feb 04, 2019 4:54 pm
Forum: Phase Changes & Related Calculations
Topic: Heat and Condensation
Replies: 9
Views: 33

Re: Heat and Condensation

Condensation is exothermic, releases heat, because it is the changing of a gas state to a liquid state.
by davidryan3f
Mon Feb 04, 2019 4:52 pm
Forum: Phase Changes & Related Calculations
Topic: Negative work
Replies: 11
Views: 51

Re: Negative work

Yes negative work will occur when the system does work on its surroundings rather than the surroundings doing work oil the system.
by davidryan3f
Mon Feb 04, 2019 4:50 pm
Forum: Phase Changes & Related Calculations
Topic: Type of systems
Replies: 12
Views: 47

Re: Type of systems

An isolated and closed system are different things. A closed system allows for the exchange of energy in and out of the system. However it does not allow matter to move in and out. On the other hand, an isolated system is completely closed off and does not allow the transfer or heat or energy.
by davidryan3f
Sun Jan 27, 2019 5:01 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy signs
Replies: 13
Views: 38

Re: Enthalpy signs

Delta H is positive when the reaction is endothermic and Delta H is negative when the reaction is exothermic.
by davidryan3f
Sun Jan 27, 2019 4:57 pm
Forum: Phase Changes & Related Calculations
Topic: Why are phase changes endothermic?
Replies: 11
Views: 48

Re: Why are phase changes endothermic?

Phase changes from solid-->liquid-->vapor are endothermic reactions because it requires an input of heat and energy to break the intermolecular forces.
by davidryan3f
Sun Jan 27, 2019 4:53 pm
Forum: Phase Changes & Related Calculations
Topic: Delta H
Replies: 11
Views: 54

Re: Delta H

H stands for enthalpy. So delta H represents the change in enthalpy during a reaction. If delta H is positive then the reaction requires energy and is endothermic. If delta H is negative then the reaction releases energy and is exothermic.
by davidryan3f
Wed Jan 16, 2019 5:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acids
Replies: 6
Views: 35

Re: Acids

A weak acid or base does not dissociate fully while a strong acid or base does indeed dissociate fully ion the solution.
by davidryan3f
Wed Jan 16, 2019 5:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and liquids in K
Replies: 6
Views: 31

Solids and liquids in K

I know that you don't include solids and liquids into the equation when calculating the equilibrium constant but could someone please explain to me why that is? Thanks friends
by davidryan3f
Wed Jan 16, 2019 4:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: % Ionization
Replies: 3
Views: 35

Re: % Ionization

To calculate the percent ionization, divide the conjugate acid or base equilibrium molarity by the acid or base initial molarity.
by davidryan3f
Sun Jan 13, 2019 5:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: True or False regarding reaction mixture [ENDORSED]
Replies: 10
Views: 47

Re: True or False regarding reaction mixture [ENDORSED]

yes that is basically the definition of equilibrium.
by davidryan3f
Sun Jan 13, 2019 5:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: solids and liquids [ENDORSED]
Replies: 4
Views: 22

Re: solids and liquids [ENDORSED]

Molarity of a solid and liquid cannot change during the course of a reaction so there is no need to include them when finding K.
by davidryan3f
Sun Jan 13, 2019 5:36 pm
Forum: Ideal Gases
Topic: Pv=nRT [ENDORSED]
Replies: 12
Views: 89

Re: Pv=nRT [ENDORSED]

Henry Dudley 1G wrote:What is the value of R?

R= 0.08206 L atm/mol K. This is given to us on tests I believe.
by davidryan3f
Sun Dec 09, 2018 3:56 pm
Forum: Naming
Topic: Naming question with anion
Replies: 2
Views: 35

Re: Naming question with anion

anions in coordination compounds will have the endings -o -ido or -ato.
by davidryan3f
Sun Dec 09, 2018 3:56 pm
Forum: DeBroglie Equation
Topic: Calculating Velocity
Replies: 5
Views: 42

Re: Calculating Velocity

yes, the two equations involving velocity are p=mv and KE= 1/2mv^2
by davidryan3f
Sun Dec 09, 2018 3:55 pm
Forum: Hybridization
Topic: Hybrid Orbitals
Replies: 4
Views: 32

Re: Hybrid Orbitals

the answer would be sp, sp2, sp3, sp3d etc
by davidryan3f
Sun Dec 09, 2018 3:53 pm
Forum: Biological Examples
Topic: Cisplatin
Replies: 3
Views: 47

Re: Cisplatin

Cisplatin has a central atom of platinum with two Cl attached and two NH3 attached. It is tetrahedral.
by davidryan3f
Sun Dec 09, 2018 3:52 pm
Forum: Bond Lengths & Energies
Topic: Shape of molecule
Replies: 4
Views: 35

Re: Shape of molecule

The greater the surface area off the molecule, the stronger the attraction/bond will be.
by davidryan3f
Sun Dec 09, 2018 3:51 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Size and Polarizability
Replies: 4
Views: 41

Re: Size and Polarizability

the size of the atom refers to the atomic radius. Atomic radius increases as you go down the periodic table and to the left on the periodic table.
by davidryan3f
Sun Dec 09, 2018 3:49 pm
Forum: Air Pollution & Acid Rain
Topic: Basic Rain
Replies: 5
Views: 46

Re: Basic Rain

I don't think it could physically happen in the conditions present on earth but it is certainly chemically possible.
by davidryan3f
Sun Dec 09, 2018 3:49 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: acid rain formula
Replies: 4
Views: 42

acid rain formula

what is the chemical equation for acid rain?? I think we went over this in class but I missed it in my notes.
by davidryan3f
Sun Dec 09, 2018 3:47 pm
Forum: Coordinate Covalent Bonds
Topic: polydentates
Replies: 5
Views: 47

Re: polydentates

Either simply memorize the common polydentates or draw the Lewis structure to determine if has two or more bonds that attach it to the central atom.
by davidryan3f
Sun Dec 09, 2018 10:50 am
Forum: Electronegativity
Topic: Trend of Electronegativity
Replies: 9
Views: 86

Re: Trend of Electronegativity

Electronegativity increases as you go up the periodic table and as you go across the periodic table. Same goes for ionization energy.
by davidryan3f
Sun Dec 09, 2018 10:50 am
Forum: Empirical & Molecular Formulas
Topic: Mass Percent Composition
Replies: 7
Views: 147

Re: Mass Percent Composition

If it does not add up to 100%, then the question is incorrect. The elements that are apart of the compound have to add up to 100% or else there is a missing element.
by davidryan3f
Sun Dec 09, 2018 10:47 am
Forum: DeBroglie Equation
Topic: Momentum
Replies: 10
Views: 156

Re: Momentum

You will not always be given the momentum. Solve the debroglie equation algebraically. The question will always give you enough variables to solve for the missing ones.
by davidryan3f
Sun Dec 09, 2018 10:45 am
Forum: Conjugate Acids & Bases
Topic: Conjugate Bases
Replies: 7
Views: 53

Re: Conjugate Bases

Conjugate bases are the result of the acid after it donates its proton. Comjugate acids are the result of the base after it accepts its proton.
by davidryan3f
Sun Dec 09, 2018 10:44 am
Forum: Biological Examples
Topic: Cisplatin
Replies: 2
Views: 33

Cisplatin

How does the fact that the ligands in cisplatin only bind at one site help account for the way that the drug stops cell division?
by davidryan3f
Sat Dec 08, 2018 11:18 pm
Forum: Quantum Numbers and The H-Atom
Topic: Test #2 Question #5b
Replies: 2
Views: 27

Re: Test #2 Question #5b

nodal planes are the regions in which there is a zero % chance of finding an electron.
by davidryan3f
Sat Dec 08, 2018 11:16 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 18
Views: 109

Re: Speed of Light

light always travels at the same speed regardless of wavelength or amplitude. it is a constant.
by davidryan3f
Sat Dec 08, 2018 11:15 pm
Forum: Conjugate Acids & Bases
Topic: Acceptor and Donor?
Replies: 3
Views: 33

Re: Acceptor and Donor?

yes, the acid donates the proton and its conjugate receives the proton. the same goes for bases.
by davidryan3f
Sat Dec 08, 2018 11:14 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: HOCl vs HOI
Replies: 9
Views: 58

Re: HOCl vs HOI

Cl is considerably more electronegative than I, so the O-H bond is stronger than the O-I bond. therefore it is a stronger acid.
by davidryan3f
Sun Dec 02, 2018 11:48 pm
Forum: Sigma & Pi Bonds
Topic: Which bond would break first.
Replies: 11
Views: 89

Re: Which bond would break first.

the pi bond would break first because it is weaker than the sigma bond. It has a lower dissociation energy so it will break first.
by davidryan3f
Sun Dec 02, 2018 11:47 pm
Forum: Hybridization
Topic: tetrahedral
Replies: 5
Views: 28

tetrahedral

can someone explain to me why tetrahedral is sp3 hybridization?
by davidryan3f
Sun Dec 02, 2018 11:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs angular?
Replies: 15
Views: 100

Re: Bent vs angular?

Bent is just another name for angular. they are synonyms .
by davidryan3f
Sun Nov 25, 2018 4:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 7
Views: 48

Re: Molecular Shape

A molecule with a seesaw molecular geometry will have a total of 5 electron domains and one of them will be a lone pair of electrons. The molecule will have angles of 120, 180, and 90 degrees at various locations.
by davidryan3f
Sun Nov 25, 2018 4:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: electron arrangement and molecular geometry
Replies: 1
Views: 11

electron arrangement and molecular geometry

What I the difference between electron arrangement and molecular geometry? I get that molecular geometry is a more specific description of the atom but Im not sure the difference between the two terms.
by davidryan3f
Sun Nov 25, 2018 4:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: pi and sigma bonds
Replies: 9
Views: 60

Re: pi and sigma bonds

Sigma bonds have more energy because since they are stronger bonds, they require more energy to be broken than pi bonds. Therefore they have more energy themselves.
by davidryan3f
Sun Nov 04, 2018 3:22 pm
Forum: Photoelectric Effect
Topic: intensity
Replies: 4
Views: 55

intensity

how does increasing the intensity of the incoming photon affect the energy of the photon. Does it increase its energy, and if so, does that increase the number of electrons that will be emitted?
by davidryan3f
Sun Nov 04, 2018 3:19 pm
Forum: Quantum Numbers and The H-Atom
Topic: degeneracy in quantum numbers
Replies: 3
Views: 44

degeneracy in quantum numbers

Could someone explain what exactly degeneracy is in quantum numbers?
by davidryan3f
Sun Nov 04, 2018 3:18 pm
Forum: DeBroglie Equation
Topic: NUETRON DIFFRACTION [ENDORSED]
Replies: 1
Views: 48

NUETRON DIFFRACTION [ENDORSED]

Can someone explain why neutrons do not diffract?
by davidryan3f
Sun Oct 28, 2018 10:31 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 16
Views: 163

Covalent Bonds

This may be a dumb question but im a little confused. Can non metals form cations. if not, why can't they?
by davidryan3f
Sun Oct 28, 2018 10:29 pm
Forum: Ionic & Covalent Bonds
Topic: Changes in Form
Replies: 2
Views: 23

Re: Changes in Form

No, I do not believe that the state of the molecule effects the type of bond that will form.
by davidryan3f
Sun Oct 28, 2018 10:26 pm
Forum: Ionic & Covalent Bonds
Topic: the Octet rule
Replies: 21
Views: 140

Re: the Octet rule

yes, there are a few exceptions. These exceptions are hydrogen, helium, lithium, beryllium. These atoms don't need to fulfill the octet rule.
by davidryan3f
Sun Oct 07, 2018 9:28 pm
Forum: Empirical & Molecular Formulas
Topic: When to double moles
Replies: 13
Views: 120

Re: When to double moles

You can round up or down if it is within .1 of the nearest whole number.
by davidryan3f
Sun Oct 07, 2018 9:24 pm
Forum: Empirical & Molecular Formulas
Topic: Converting Units
Replies: 5
Views: 43

Re: Converting Units

Convert the units beforehand so that the math will be valid. For example in an m1v1=m2v2 problem, the volumes must be in the same units.
by davidryan3f
Sun Oct 07, 2018 9:11 pm
Forum: SI Units, Unit Conversions
Topic: What is the notation for molar mass?
Replies: 15
Views: 390

Re: What is the notation for molar mass?

I am pretty sure that it is just an uppercase M (g/mol).

Go to advanced search